High oil pressure 2000 Vortec 6.0 liter 200k mi

My well maintained 2000 Suburban 2500 with Vortec 6 liter and tow package has about 200,000 miles and is reading an oil pressure at the gauge around 70psi, which seems weirdly high to me. My mech says to count my blessing but I recently read about an oil regulator valve in the oil pump that can fail (usually failing in the closed position blocking flow) and I wondered if it may not be stuck wide open and if it might be an issue or a blessing. Or maybe just a faulty gauge?

That's actually something I would be concerned about. The pump is simply pushing oil. Under ideal conditions, you're looking for flow, not pressure. In fact a low pressure high flow condition is best for lubricating and protecting your engine. The oil pressure must maintain a minimum, of course, to get the oil where it needs to go (when it stops, that's a bigger problem than high pressure). Kudos to you for watching the gauge so closely.

High pressure conditions are generally caused by restriction of some sort. This may or may not be at the filter. A quick change of the filter will answer that question, obviously. If your pressure is consistently high, this suggests your oil flow system is clogged in one or more places, or your oil viscosity is too high (A question here would be "do you change your own oil, and can guarantee what went in?" The follow-up to that would be, "Did someone accidentally put a high viscosity oil in the system?").

At 200K miles you might simply have deposits and build-up restricting flow. Common methods of removing such include using an engine flush or a detergent of some kind in your oil. I personally don't recommend engine flushes (especially on such high mileage vehicles) as the chunks of stuff that can break off can cause more clogging and damage if they're not adequately removed. For example, you may do an engine flush and 5 minutes of idle later, change your oil. The particles in your engine may continue to slough off, though, and then clog your next filter lickity-split (highly technical term). Then you're running the by-pass and actually damaging the engine with particle debris. It's just not worth it to me.

Other folks/mechanics often use a quart of transmission fluid (high detergent) in your oil and will have you run the vehicle for 20-100 miles then change the filter and oil. Some mechanics will have you run up to 500 miles this way. For me, again, this is a high detergent and can loosen debris faster than you can take it out. Changing the filter an oil more frequently with a transmission fluid blend can help reduce the build-up.

Personally, I love using Marvell Mystery oil to solve this problem. It's a light detergent and a very low viscosity oil, safe for your engine. Replace 1 quart of your oil with this stuff, and you should see an immediate reduction in oil pressure (it'll make everything a bit thinner making it flow easier through the restricted areas). At the same time, it will SLOWLY dissolve and remove deposits. Run this setup for 500 miles, then change your oil and filter. Run it again for 1000 miles and change the oil and filter, and then again for 1500 miles and change your oil and filter. This should slowly reduce the buildup in your system and restore some lost power in your engine to boot.

The bottle will tell you it's safe to run full time in your engine, and I know folks that have done that without problems. For me, the viscosity is just a little lower than I'd like, and I simply run a high quality synthetic instead.

Either way, this is definitely something you should be concerned with, as high pressure indicates blockage. The back side of the sump, btw, will have negative pressure as it's drawn into the pump. The high pressure condition basically means stuff isn't squirting into the places it needs to fast enough. Probably not enough to restrict oil transfer all together, but it sure won't be helping things.

Hope this helps!

BTW, as with ANY build-up removal process, there's always a chance of something going awry. Short of a full tear-down and clean, though, this is the best method I've been able to come up with with the lowest risk. Maybe others will have ideas on how else to remove blockage.

Cheers,

Skippy.

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One more thing to check... Is your oil filter bulging in any way? This could indicate a bad pressure relief valve and or spring on the oil pump.

A few questions.
1. What was the normal oil pressure reading before it went 70 psi?
2. What type of oil (conventional or synthetic) and viscosity are you using?
I only use synthetic oil because I hold on to vehicles for a long time and there is no sludge build up.
3. Any recent work done?

1st, thanks for the great responses. To hit Skippys very nice in depth response and a few that'd overlap:

**I've owned the truck for a year and only drive it maybe 1000 miles a year exclusively pulling the boat. It's not using oil, is in great shape, I knew the former original owner who was pretty meticulous about maintenance so it has "normal to below avg" use and is in above avg cond. No recent work done that I'm aware of.

** I changed the oil/filter last year, and just last week again w 10/30 conventional oil. It had only run maybe 1000mi but that was pulling a full time 10,000lb load. The oil looked moderately bad for only 1k mi but that's pretty tough road time in typical Florida heat for an older 3/4 ton too. The filter was in fine shape.

**After reading Bazaar and JCats comments about their hwy speed oil at 60psi along with a few from other forums at the same psi I'm wondering if 60 is the new 40 and to be expected. 70psi would be higher than I've read anywhere so I may have to add a new pressure gauge to reaffirm the dash gauge if it is actually that far up.

** If it sounds reasonable, I have a leaking oil pan gasket to replace so I think I'll replace a quart of my recently changed oil with some marvel mystery oil and run it 100mi , then pull the oil pan to see what I'm looking at inside the crank case and change the oil/filter again. It'll get new oil/filter every 1000mi after that considering the constant load.

**The truck also gets a much bigger trans cooler this weekend thanks to the posted details/results on this forum. My tranny temps were at 190* at 65mph on flat interstate roads so I'm hoping for <160* with a very simple mod up front.

Thanks again for the helpful input and your time spent posting. You have a great forum here and I'm still open to other input. I'll add to the post when I have results that'd be relevant. Mike